In this type of technical field, 3GPP that is a standardization group of W-CDMA studies a communication scheme that becomes a successor to the wideband code division multiple access (W-CDMA) scheme, the high speed downlink packet access (HSDPA) scheme, the high speed uplink packet access (HSUPA) scheme and the like, that is, 3GPP studies Long Term Evolution (LTE).
In the LTE, an inactive (idle state) user apparatus can move between cells while performing discontinuous reception (DRX) of a paging channel, and the user apparatus is managed for each of tracking areas (TA) including one or more cells while maintaining the location registration state to be the newest state. In the idle state, there is no context of the user apparatus in the base station. The location registration state is managed by an upper station. When the network calls a user apparatus which is in an idle state, the paging channel is transmitted all together in all cells belonging to the tracking area in synchronization with DRX timing of the user apparatus, so that an incoming call arrives at the user apparatus.
By the way, in the LTE, mainly from the viewpoint of battery saving, even an active user apparatus performs discontinuous reception as necessary. For example, in a service in which internet access is performed, since traffic arrives like bursts, there is a case in which a considerable length of time elapses between data transmission and next data transmission. For example, a user downloads a web page and reads the page, then, after a time elapses, the user downloads a next page. In this case, discontinuous reception is performed.
In a connected state, there is the context of the user apparatus in the base station, so that the network ascertains the position of the user apparatus in units of cells. In order to decrease processing for generation/deletion of context and to decrease signaling for establishing lines in the base station, it is effective to apply discontinuous reception in a connected state without changing the state of the user apparatus to the idle state. In addition, burst packets can be transmitted with less delay while avoiding battery consumption.
The user apparatus performing discontinuous reception operates while switching between an awake state and a sleep state in a predetermined cycle (DRX cycle), and the user apparatus receives a L1/L2 control signal in the cycle. The user apparatus demodulates the L1/L2 control signal so as to check presence or absence of information destined to the user apparatus. The information may include information indicating that there is downlink data, resource blocks and a data format (data modulation scheme and the like) used when there is the downlink data, and resource blocks and a data format that can be used for next uplink data transmission, and the like. If there is information destined for the user apparatus, the user apparatus receives downlink data according to the information, for example. If not, the state of the user apparatus changes from the awake state to the sleep state, so that the user apparatus waits until next wake-up timing.
Generally, the longer the DRX cycle is, the larger the effects of battery saving or power savings become. But, it should be noted that DRX also affects QoS. For example, the non-patent document 1 discloses a technique for setting DRX cycle for each radio bearer.    [Non-patent document 1] 3GPP contribution document, R2-070463, Feb. 6, 2007